added mock handlers for VpnUsersCfgCommand and RemoteAccessVpnCfgCommand in the simulator

Signed-off-by: Koushik Das <koushik@apache.org>
added delete iso api to the simulator in the smoke tests, this will fix test_03_delete_iso when run against a simulator

Signed-off-by: Koushik Das <koushik@apache.org>
CLOUDSTACK-5080: Hypervisor Capabilities table missing entry for Simulator

Signed-off-by: Prasanna Santhanam <tsp@apache.org>